Court cases containing bloodstain pattern analysis have a history of change and progression, but even today the methods are not perfect. The effective use of bloodstain pattern analysis has been present within crime scene history for approximately 500 years. In 1514, the first use of bloodstain pattern analysis provided information on a crime concerning Richard Hunne in London, England, who was found dead in his jail cell. Though first thought to be suicide, it was later revealed to be a homicide based on the large quantity of blood found near the body that was shed before his death. Bloodstain analysis methods, technology, and understanding have greatly improved, though even in the year 2000, the International Association of Bloodstain Pattern Analysts (IABPA) recognized its fallibility and its lack of validity in court. Bloodstain pattern evidence today can provide two types of information: underlying factual observations of the blood stain, as well as a fact-based opinion of what the stains mean or infer. There is a certain amount of expert estimation involved in the identification of bloodstain origin and analysis. The temptation to overstep the boundaries of factual knowledge to that of opinion has caused discrepancies within the court. To press the knowledge of the crime scene from an expert opinion has been tempting when it lines up with the view of the court. In theory this would have aided in the validity of bloodstain analysis patterns in court, when in reality it may have hindered its primary purpose to expose truth. The limits of bloodstain analysis may occur because of the nature of events, nature of the crime scene, or the inconclusive nature of other associated evidence.
The first time blood stain analysis evidence was qualified to be used in Canadian court was in 1976. The emphasis was not on the pattern of blood in the evidence, but rather the age of the bloodstain. At this time, the pattern did not advance the evidence and did not aid in the development of theories of attack. Bloodstain pattern analysis evidence has been present in American court cases since late 1940s, and continues to be relevant to cases today. Key contributors in this history were people such as Dr. Eduard Piotrowski, a Polish assistant at the Institute for Forensic Medicine. In 1895, he designed scientific experiments to show blood dynamics using multiple theories. He published "Concerning the Origin, Shape, Direction and Distribution of the Bloodstains Following Head Wounds Caused by Blows," which helped pioneer investigations using this method. These methods were used in crime scene analysis, wherein blood splatter was analyzed using trigonometry to determine the origin of an impact event. However, this method neglected the fact that bloodstains are two dimensional, unlike the original drops of blood. Bloodstains always appear bigger than the initial drop, and are more elliptical in shape. This method as well as those further developed are best used as an approximation. Previous origin reconstruction methods used strings and lasers to trace back to a single point of origin. Ideally, blood spatters would trace back to a point, but in reality, it is never just one point and so, this idea creates a false sense of “exactness”. The size and shape of the locus of origin points may provide information about the size and shape of a weapon, but the lines from the bloodstains can trace the origin further back then the actual location. In the past, such methods have sometimes resulted in false accusations. In 1995, Dr. Paul Kirk submitted his findings of the Sam Sheppard case. Kirk had identified the position of the assailant and the victim, and his research revealed that the attacker struck the victim with his left hand, by determining that the stain shape was affected by the velocity of the blood drop. The ability to use these methods to make these assumptions were a new idea in the field of forensic science. Furthermore, the first training course in bloodstain training was given by Herbert Leon MacDonell in 1973 in Jackson, Mississippi. In 1983, the International Association of Bloodstain Pattern Analysts was founded by a group of bloodstain analysts to help develop the emerging field of bloodstain pattern analysis.
Modern techniques now use approximate areas of convergence (origin) over points of convergence (origin). An area of convergence is determined by the direction of travel of several blood spatters, which can be approximated using convergence points and impact angles. It is better to use a combination of techniques that would otherwise provide insufficient information on their own (such as both hair sampling and bloodstain analysis combined). The following should be observed/considered: multiple areas of convergence (on two or more surfaces at right angles), blockage (void) patterns, blood transfers from people and objects, computer softwares (e.g. HemoSpat). Unlike DNA, fingerprints and drug assays, bloodstain pattern evidence is more difficult to standardize. It is necessary to consider spatter events, transfer, drying, coagulation, and firearm dynamics. There are many variables that impact blood spatter analysis (e.g. blood drop size, velocity of weapon at contact, velocity of blood drop, type of weapon, blood source/nature of injured blood vessel, environmental conditions, and properties of target surface). Although technology has progressed a great deal since Dr. Kirk’s time, forensic scientists are still influenced by his logic.
Over the years the cumulative research that has gone into bloodstain analysis has created the following procedure: first, label a collection of blood spots or stains as blood spatters; classify the blood spatter (impact, cast off, arterial spurt, blood into blood, or respiration) based on blood spot shapes; finally, consider velocity and direction of travel (can also be approximated based on shape). It should be noted that these techniques are not perfect and will inherently add variability and error to the analysis of a crime scene.
The Canadian Court system has provided criteria to which blood stain analysis evidence may be permitted in court: the evidence must have relevance to the issues in the case; the evidence is necessary to the conclusions made in court which a layman could not have found; the evidence must not transgress any exclusionary rule; also the evidence must be provided and analysed by a properly qualified personnel. Canadian courts do recognize that bloodstain patterns must be interpreted by trained scientists and require skills that are not naturally obtained. The pattern analysis can provide a series of information including: scene identification, narrative of events, identifying accused persons, as well as connecting participants to the event.
One instance in which bloodstain pattern analysis was key was in the case surrounding the death of English 13-year-old Billie-Jo Jenkins in 1997, who was initially thought to have been murdered by her foster father Sion Jenkins. Sion Jenkins was charged with murdering Billie-Jo by battering her head using a tent peg, and was sentenced to life imprisonment in 1998 based on the bloodstain pattern analysis of forensic scientists. As a result of a fine spray of blood, 158 microscopic spots of Billie-Jo’s blood were found on Sion’s clothing. Forensic investigators believe this was caused by impact spatter. By examining the shapes, sizes, and impact angles of the blood spots, it was believed that they must have originated from the impact of Sion standing over his foster daughter and hitting her over the head repeatedly. This, however, was not the final word. An expert in lung disease, David Denison was called to re-examine the case. Rather than impact spatter, Denison believed the blood spots were actually caused by pulmonary interstitial emphysema, a condition that causes a build-up of pressure in the lungs (caused by being attacked with the tent peg, just not by Sion). Sion claimed to have come home to find Billie-Jo already dead, and Denison believes that the spatter of blood on his clothing must have occurred when Sion tried to move her body, causing the blood trapped in her airways being released from her nose and/or mouth. This is referred to as expiration spatter. To prove his theory, Denison reconstructed the crime scene and took into account the properties of pulmonary interstitial emphysema; using this method he was able to reproduce a similar spatter pattern to what was observed on Sion’s clothing. As a result of this new evidence, Sion Jenkins was eventually acquitted in 2006. Though Sion has been released from jail, many forensic experts around the world are still puzzled by this case and continue to scrutinize the tiny bloodstains. While bloodstain pattern analysis has been used for decades as a key tool in the investigative process, and new approaches to old techniques have become available, it is important to note that bloodstain pattern analysis has by no means become a “perfected” method as a result of time. There exists an inherent variability when examining the bloodstains of a case; error is introduced by the methods used, and biases may influence analysis as well (e.g., a forensic investigator examining blood spatter versus a lung doctor).
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